Which of the following statements is/are correct?

Options

A. Adenine and cytosine are substituted purines
B. the sugar present in DNA nucleoside is deoxyribose
C. RNA contains uracil instead of thymine present in DNA
D. In nucleic acids, a phosphate group is bonded to a hydroxyl group of sugar.

Answer

To determine which statements are correct regarding nucleic acids and their components, let's analyze each option step by step.

### Step-by-Step Solution:

1. **Option 1: Adenine and Cytosine are substituted purines.**
- **Analysis:** Adenine is indeed a purine, but Cytosine is a pyrimidine. Therefore, this statement is incorrect.
- **Conclusion:** **Incorrect**

2. **Option 2: Sugar present in DNA nucleoside is deoxyribose.**
- **Analysis:** The full form of DNA is deoxyribonucleic acid, which indicates that the sugar component of DNA is deoxyribose. This statement is correct.
- **Conclusion:** **Correct**

3. **Option 3: RNA contains Uracil instead of Thymine present in DNA.**
- **Analysis:** In RNA, uracil replaces thymine, which is found in DNA. This statement is also correct.
- **Conclusion:** **Correct**

4. **Option 4: In nucleic acid, the phosphate group is bonded to a hydroxyl group of sugar.**
- **Analysis:** In nucleotides, which make up nucleic acids (DNA and RNA), the phosphate group is indeed bonded to the hydroxyl group of the sugar molecule. This statement is correct.
- **Conclusion:** **Correct**

### Final Summary:
- **Option 1:** Incorrect
- **Option 2:** Correct
- **Option 3:** Correct
- **Option 4:** Correct

Thus, the correct statements are Options 2, 3, and 4.

---